now this is pretty obvious but here it goes anyway

i play g/w - Sometimes you can pull this off

  
first turn green mana  and a birds 
second turn a white mana and play a noble panther
third turn play a green mana now u have 2 green and 1 white and a birds play 2 armadillo cloaks on the panther making him a  7/7 trample on turn 3 
4th turn play another white mana play a serras embrace and now u have a 9/9 flying  trample  doesn't tap 2 attack first strike on turn 4 maybe even go 2 
turn 5 and play another green play 2 more cloaks and he's 13/13 first strike flying trample doesn't tap 2 
  
                           from  Da_man